Who's who: These were the top 5 Houston energy transition interviews of 2023

Here were the top energy transition interviews on EnergyCapital — according to its readers. Photos courtesy

Editor's note: As the year comes to a close, EnergyCapital is looking back at the year's top stories in Houston energy transition. EnergyCapital launched specifically to cover the energy transition community — and that includes the people who power it. With weekly interviews, we spoke to dozens of these individuals and some resonated more than others to readers. Be sure to click through to read the full interviews or stream the podcast episode.

Kelsey Hultberg, executive vice president of corporate communications and sustainability at Sunnova Energy

Kelsey Hultberg, executive vice president of corporate communications and sustainability at Sunnova Energy, joins the Houston Innovators Podcast. Photo courtesy of Sunnova

Several years ago, Kelsey Hultberg decided to make a pivot. Looking for a role with career growth opportunities, the communications professional thought she'd find something at an oil and gas company, but then she met John Berger, founder and CEO of Sunnova, who was looking for someone to stand up their communications team amidst the solar energy company's growth.

"He hooked me," Hultberg shares on the Houston Innovators Podcast. "He said, 'I've got big plans for this company. I see where this energy industry is going, I see that we're prime for a transition, and I want to take this company public.' And I started a few weeks later."

Hultberg has been telling the story for Sunnova — which equips customers with solar and storage technology, providing them with energy independence — ever since, through scaling, new technologies, and its IPO in 2019.

Continue reading the interview from October.

PJ Popovic, CEO and founder of Rhythm Energy

Houston-based Rhythm Energy CEO and founder, PJ Popovic, discusses the landscape of Texas' energy market and how renewables should be incorporated. Photo courtesy of Rhythm

After experiencing the hottest day on record this past Fourth of July, PJ Popovic — CEO and founder of green energy retailer Rhythm Energy — explained what extreme temperatures like these mean for Texas’ energy market and the role renewables will play in addressing increased demand response.

Headquartered in Houston, Rhythm Energy launched two years ago and offers a variety of 100 percent renewable energy backed plans, from wind to solar. Popovic discussed with EnergyCapital where he thinks renewables fit into Texas’ energy consumption and grid reliability issues in an interview.

Continue reading the interview from July.

Aniruddha Sharma, co-founder and CEO of Carbon Clean

Aniruddha Sharma of Carbon Clean weighs in on his North American expansion, the impact of the Inflation Reduction Act, and more. Photo via carbonclean.com

Earlier this year, a growing carbon capture company announced its new North American headquarters in Houston. Now, the company is focused on doubling it's headcount before the end of 2023 to meet demand.

Carbon Clean, which has a technology that has captured nearly two million tons of carbon dioxide at almost 50 sites around the world, opened its new office in the Ion earlier this year. The company is now building out its local supply chain with plans to rapidly expand.

In an interview with EnergyCapital, Co-Founder, Chair, and CEO Aniruddha Sharma weighs in on the new office, how pivotal the Inflation Reduction Act has been for his company's growth, and the future of Carbon Clean.

Continue reading the interview from August.

Vibhu Sharma, founder of InnoVent Renewables

Vibhu Sharma founded InnoVent Renewables to make a sustainable impact on tire waste. Photo courtesy

With over a billion cars currently on the road — each with four tires that will eventually end up discarded, one Houstonian is hoping to create the infrastructure to sustainably dispose of tire waste now and into the future.

Announced earlier this month, Vibhu Sharma founded InnoVent Renewables to establish production facilities that utilize a proprietary continuous pyrolysis technology that is able to convert waste tires, plastics, and biomass into fuels and chemicals.

In a Q&A with EnergyCapital, Sharma explains his plans to sustainably impact the tire waste space and his vision for his company.

Continue reading the interview from September.

Cindy Taff, founder and CEO of Sage Geosystems

In a Q&A with EnergyCapital, Cindy Taff of Sage Geosystems explains why she's so optimistic about geothermal and her company's technology. Photo courtesy of Sage

Geothermal energy is an integral part of decarbonizing the energy industry, and Sage Geosystems CEO Cindy Taff believes her company's tech has what it takes to lead the way.

Founded in Houston in 2020, Sage Geosystems is focused on two business lines — energy storage and geothermal. In addition to developing these technologies, Taff says Sage has "cracked the code" on both reducing costs and maximizing electricity output. Sage has customers ranging from Nabors, the world’s largest land-based drilling company, and Virya LLC, an investor in climate ventures with high impact of eliminating global greenhouse gas emissions or sequestering CO2

In a Q&A with EnergyCapital, she explains why she's so optimistic about geothermal and her company's technology.

Continue reading the interview from December.

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A View From HETI

Fervo Energy claimed a top 10 spot on Time magazine and Statista’s new list of America’s Top GreenTech Companies of 2025. Photo via Getty Images.

The accolades keep rolling in for Houston-based Fervo Energy, a producer of geothermal power.

Fervo lands at No. 6 on Time magazine and Statista’s new list of America’s Top GreenTech Companies of 2025. The ranking recognizes sustainability-focused companies based on factors such as impact, financial strength, and innovation.

Time notes that Fervo broke ground in 2023 in Utah on what the company claims will be the world’s largest geothermal plant. The plant is scheduled to start supplying carbon-free electricity to the grid next year and to reach its 400-megawatt capacity in three years.

“Technologies like this only make a difference if we deploy them at large-scale in a way that can reduce carbon emissions and increase the reliability of the grid,” Fervo CEO Tim Latimer told Time in 2023.

The startup was named North American Company of the Year by research and consulting firm Cleantech Group for 2025. Fervo topped the Global Cleantech 100, Cleantech Group’s annual list of the world’s most innovative and promising cleantech companies.

Last year, Fervo also made Time’s list of the 200 Best Inventions of 2024. Fervo was recognized in the green energy category for its FervoFlex geothermal power system.

Founded in 2017, Fervo is now a unicorn, meaning its valuation as a private company exceeds $1 billion. The startup’s valuation is estimated at $1.4 billion. According to PitchBook data, the company raised $634 million in the fourth quarter of 2024.

In all, eight Houston-area companies appear among the top 250 greentech companies ranked by Time and Statista. Other than Fervo, they are:

  • No. 43 Lancium Technologies, an energy storage and distribution company
  • No. 50 Solugen, a producer of sustainable chemicals.
  • No. 56 Quaise Energy, which specializes in terawatt-scale geothermal power.
  • No. 129 Plus Power, a developer, owner and operator of battery storage projects.
  • No. 218 Dream Harvest, which promotes sustainable vertical farming.
  • No. 225 Cemvita, which uses synthetic biology to convert carbon emissions into bio-based chemicals.
  • No. 226 Syzygy Plasmonics, which decarbonizes chemical production.
Vermont-based BETA Technologies claimed the No. 1 spot. The company manufactures electric aircraft.

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